This application is the national phase under 35 U.S.C. xc2xa7371 of PCT International Application No. PCT/DE00/01201 which has an International filing date of Apr. 17, 2000, which designated the United States of America, the entire contents of which are hereby incorporated by reference.
The invention generally relates to a connecting apparatus for a number of components. More preferably, it relates to a connecting apparatus including a connecting element which has a shaft which passes through through-openings which are aligned with one another in the connection, the connection element including an insertion end and including a holding end opposite it. More preferably, the components can be braced with respect to one another by twisting the connecting element. In this case, the term components preferably refers, in particular, to enclosure parts or shells of switching devices which are installed in a row or low-voltage switching devices, for example of circuit breakers.
Circuit breakers and other devices which are installed in a row, as well as enclosure parts or halves thereof, are normally connected via one or more poles by nuts and bolts, clips or brackets, or rivets, with one enclosure shell and one cover shell having to be connected to one another for each pole. It is intended to be possible firstly to produce such connections cost-effectively and simply, and such that they can be installed easily. Secondly, compression loads which occur as a consequence of arching influences are intended to be absorbed by the connections, and tolerances are intended to be compensated for, while allowing the enclosure shells to expand and ring when subjected to environmental conditions. A specific prestressing force is also intended to be exerted on the enclosure shells in order not only to ensure that the parts to be connected are protected against twisting, but also to ensure that the connection is protected against being inadvertently loosened.
While the use of a screw connection for connecting the components or enclosure shells to one another is, firstly, costly and; secondly, the screw connection must be secured against inadvertently becoming loose, for example by means of varnish, a riveted joint offers only a small amount of compensation for tolerances in its longitudinal direction.
This is particularly true when the tolerances to be compensated for are additive. Furthermore, riveted joints easily bend when carrying out a riveting process using relatively long rivets. In addition, additional centering pieces have frequently been used in the past to protect the individual poles against twisting, even though this results in additional manufacturing and production costs.
At least two clips or brackets must be used, in a likewise costly manner, for a clip or bracket joint, which is likewise frequently used. In this case, the poles are firstly braced with respect to one another with only a small clamping force while; secondly, the clips or brackets can easily become loose, resulting in the risk of manipulation. A bonded joint, which has likewise been used in the past, does not allow the individual components to be dismantled without destroying them. Furthermore, it does not ensure that the components are adequately braced with respect to one another.
A connecting element which is manufactured from a flat strip material is known from German Utility Model DE 83 22 594 A1, and this can also be used for circuit breakers having an elongated shaft, whose two shaft ends are T-shaped by integrally formed tabs. In order to insert the known connecting elements into the mutually aligned through-openings or holes in the components to be connected, one of the shaft ends is slotted such that the T-shaped holding or fixing tabs can be interlaced in the direction of the shaft longitudinal axis. This admittedly results in this shaft end being matched to the shaft width. However, this configuration necessarily leads to the cross section of the shaft, and hence the connecting element, being weakened, with the consequence that the cross section must be deliberately weakened over the entire shaft length by equidistant holes. Admittedly, it makes it possible to achieve a uniform material load and to avoid any weak point. However, this weakening of the cross section leads to a considerable reduction in the shaft cross section that can be loaded and hence to a reduction in the bracing force which is intended to be achieved by twisting the shaft, resulting in the length of the connecting element being reduced. Furthermore, during the twisting process, the entire slot, which is lengthened by an elongated hole, must be covered by using a tool at the corresponding shaft end, and the opposite shaft end must be held in order firstly to secure this shaft end against rotation at the same time and; secondly, in order to achieve a tensile force, and hence a bracing force, which is as uniform as possible at the shaft ends. Furthermore, the complicated bending-in and bending-out mechanism with the slotted shaft end indicates that a number of twisting operations are required in order to ensure that the length of the connecting element is reduced sufficiently to brace the components.
The invention is thus based on an object of specifying a connecting apparatus of the type mentioned initially in which the disadvantages are avoided.
According to the invention, this object is achieved by the features of claim 1, for example. Alternatively, this object is achieved according to the invention by the features of claim 2, for example. For this purpose, the connecting element includes, at the insertion end, two fixing lugs which are bent in the form of a circular arc in an initial state and are bent out radially in the mounting state. Alternatively, two fixing lugs are provided at the insertion end of the connecting element, which extend like a fork in the shaft longitudinal direction in an initial state, and are bent out radially in the mounting state.
In both alternatives, in the mounting state before twisting of the connecting element, which is preferably manufactured by stamping from flat strip material, this shaft end, which is also used as the insertion end, is expediently inserted in a positively locking manner in a mounting depression, which is associated with the insertion end and opens into the corresponding through-opening.
In the first alternative, the insertion end opposite the holding end is initially expediently designed in a T-shape in the final state. Subsequently, it can then be changed to the initial state, with the fixing lugs bent inward in a circular shape, by using a bending process to match it to the external dimensions of the shaft. In the mounting state, that is to say after insertion of the connecting element into the through-openings, the fixing lugs are then bent out radially.
In order to allow the insertion end of the fixing lugs to be bent outside the component or enclosure part facing this end, a mounting depression which holds the opposite holding end of the connecting element is designed in two steps. The stepped internal contour is expediently formed by two notches which run at an angle to one another, preferably at right angles to one another, have a different notch depth, and define two different holding positions.
When the holding end of the connecting element is being fixed in position, the insertion end, which is provided with the fixing lugs, projects out of the mounting depression associated with said insertion end in a first comparatively deep position within the mounting depression which holds the holding end, and projects beyond the component or enclosure arrangement, so that the fixing lugs can be bent out radially in a simple manner. Following this bending process, the connecting element is pulled back and is fixed in a second position, which is displaced or offset axially outward with respect to the first position. In this case, the insertion end is at the same time pulled completely into this mounting depression that is associated with it.
The desired bracing force to brace the components or enclosure parts to one another is then produced by twisting the shaft of the connecting element. This is done by attaching an appropriate twisting tool to the insertion end, which is provided with the bent-out fixing lugs.
This embodiment is particularly suitable for connecting multipole circuit breakers having a corresponding number of enclosure and cover shells.
In the second alternative, in which the insertion end of the connecting element is designed like a fork, the two fixing lugs which extend in the shaft longitudinal direction in an initial state are integrally formed on the shaft end in such a manner that they form a direct, straight-line extension of the shaft, without any projection at the sides. In the mounting state, these fixing lugs, which are preferably formed by a stamped-out region at the insertion end and run parallel to one another, are bent out radially. In this case, the outward bend can be produced both in the shaft plane and transversely with respect to it.
In this embodiment, the connecting element is once again twisted by bending the fixing lugs out once the positive lock has been produced. In this case, the positive lock in the mounting state likewise indicates that the number of turns that need to be made when twisting the shaft is particularly low, and, in particular, is just one turn.
In one advantageous embodiment, a mounting depression which holds the holding end of the connecting element and is aligned with the through-openings is designed as a centering cone, with the holding end itself being formed conically in order to form a mating surface corresponding to the centering cone. This allows reliable self-centering of the connecting element within the mutually aligned through-holes in the components. At the same time, when the connecting element is twisted, a tensile force which is uniform over its cross-section is exerted on the opposite shaft end. Furthermore a friction force which is sufficient to prevent the holding end from being rotated at the same time is advantageously produced on the basis of the comparatively large mutually corresponding mating surfaces of the centering cone on the one hand and of the centering cone at the holding end on the other hand. There is thus no need for the two shaft ends of the connecting element to be held firmly.
The advantages achieved by the invention are, in particular, that, insertion of a connecting element which is expediently in the form of a flat strip and has fixing lugs which, in the initial state, are either bent in a circular shape or extend without any radial projection beyond the shaft external dimensions in the shaft longitudinal direction indicates that it is particularly simple to insert the connecting element into mutually aligned through-openings in components which are to be connected to one another. Furthermore, the components can be braced to one another by twisting the connecting element through one and a half turns or one turn (xc2xd times or once) without weakening the material.
The connecting element provided for this purpose is, firstly, particularly simple and, secondly, is particularly robust since the material cross section is not weakened, that is to say in particular the shaft has no holes or slots. The connection can also be made in situ in a particularly simple manner. When using galvanized steel strip or stainless material, this furthermore results in reliable corrosion protection. One major advantage is that it is possible to use already existing rivet holes or bolt holes in the enclosure parts.
Since the positive lock, at the insertion end of the shaft, is actually produced in the mounting state and before the turning or twisting of the connecting element by bending the fixing lugs radially outward or over, the reduction in the length of the connecting element required to apply the necessary bracing force. Hence, the required torsional movement, are particularly short and, in particular, are considerably shorter than in the case-of the cited prior art according to DE 83 22 594 U1.
The formation of a centering cone in the mounting depression which holds a correspondingly conical holding end of the connecting element furthermore results, firstly, in centering and; secondly, in a high friction force, so that a particularly high clamping force with simple handling at the same time is achieved when bracing the components. Furthermore, a particularly small turning or twisting distance is achieved when twisting the connecting element in order to brace the components, with self-centering at the same time. Only one connecting part is required in this case, even for multipole devices with a corresponding number of enclosure parts or shelves for each such connecting point.